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2022 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Matthias Epple ◽  
Joachim Enax ◽  
Frederic Meyer

Dental erosion is a common problem in dentistry. It is defined as the loss of tooth mineral by the attack of acids that do not result from caries. From a physico-chemical point of view, the nature of the corroding acids only plays a minor role. A protective effect of fluorides, to prevent caries and dental erosion, is frequently claimed in the literature. The proposed modes of action of fluorides include, for example, the formation of an acid-resistant fluoride-rich surface layer and a fluoride-induced surface hardening of the tooth surface. We performed a comprehensive literature study on the available data on the interaction between fluoride and tooth surfaces (e.g., by toothpastes or mouthwashes). These data are discussed in the light of general chemical considerations on fluoride incorporation and the acid solubility of teeth. The analytical techniques available to address this question are presented and discussed with respect to their capabilities. In summary, the amount of fluoride that is incorporated into teeth is very low (a few µg mm−2), and is unlikely to protect a tooth against an attack by acids, be it from acidic agents (erosion) or from acid-producing cariogenic bacteria.


Author(s):  
Yu.Yu. Pomorova ◽  
◽  
V.V. Pyatovsky ◽  
D.V. Beskorovayny ◽  
Yu.M. Serova ◽  
...  

Cultivation of oil crops of Brassicaceae family is an important part of agricultural production in many countries. Currently, interest to Brassicaceae crops is caused with their high productivity, diverse fatty-acid composition of oil of the modern cultivars, and a possibility to use them by various ways. Vegetable oils produced from Brassicaceae crops are, on the one hand, a basis of a rational human nutrition, on the other hand, this is a necessary raw material for the different industries. A balance between general chemical and amino acid compositions of protein allows using it in production of compound animal feeds and foods based on vegetable protein, having high nutritional value and useful technological characteristics (oil, protein, and essential amino acids contents). This paper presents a comparative description and principal features of the general chemical and amino acid composition of some oil crops of the Brassicaceae family. Analysis of the Russian and foreign literary sources proves the importance of further development and studying in this direction with the aim of breeding new cultivars with desired properties and providing domestic food industry with quality and safe products.


Author(s):  
Arti Mourya ◽  
Sudip K. Sinha ◽  
Bidyut Mazumdar

Abstract The use of a voltammetric sensor to measure hazardous elements has gotten a lot of coverage. The electrochemical sensor in this study was modified with cerium dioxide (CeO2) and blast furnace slag (BFS), which opens up new possibilities for improving the electrocatalytic properties of the fabricated sensor. In general chemical kinetics or mass transport can restrict the reactions involved in electrochemical detection. The prepared electrodes were tested against potassium ferricyanide, K3Fe(CN)6 solution by cyclic voltammetry. Cyclic voltammetry was used to investigate the chemical reactions involve during redox process. The electron transfer kinetics, chemical rate constant, and diffusion characteristics of reactions can all be extracted using this method. Further this sensor was applied in the detection of lead and copper ions in aqueous solution. The results show that the redox reaction is a one-electron transfer mechanism with high selectivity and sensitivity. The value of transfer coefficient (α) for the electrode reaction was calculated as 0.61. Also the calculated heterogeneous electron transfer rate constant (Ks) of the modified electrode was 2.41.


Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2414
Author(s):  
Yanan Chen ◽  
Yichen Zhang ◽  
Jiasheng He ◽  
Jiquan Zhang ◽  
Qiuling Lang ◽  
...  

Clean groundwater resources are vital to human health. To evaluate groundwater quality in the Songnen Plain (Jilin), a field investigation sampling test, multivariate statistical analysis, and spatial analysis were conducted based on a geographic information system. The main substances exceeding the standard were screened out, and the main controlling factors affecting groundwater quality were discussed. The research result showed that nine components exceeded groundwater standards by approximately 10%: Al, total hardness (TH), total dissolved solids (TDS), Mn, As, NO3−, Fe, F−, and BaP. The over-standard of TDS and TH in groundwater are mainly distributed in the geological environment conditions and unreasonable exploitation and utilization of groundwater in this area. The results of the multi-index evaluation showed that the most important factors affecting groundwater quality were general chemical indices, followed by inorganic toxicology and heavy metals. Controlling the overexploitation of water resources, controlling agricultural activities and sewage discharge, and implementing water conservation systems are the main pathways to improve water quality in the study area. The research results can provide a reference for groundwater pollution control and water resource protection in the Songnen Plain (Jilin).


Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1045
Author(s):  
Hairui Liu ◽  
Zuhong Zhang ◽  
Feng Yang ◽  
Jien Yang ◽  
Andrews Nirmala Grace ◽  
...  

Lead-based perovskite solar cells had reached a bottleneck and demonstrated significant power conversion efficiency (PCE) growth matching the performance of traditional polycrystalline silicon solar cells. Lead-containing perovskite solar cell technology is on the verge of commercialization and has huge potential to replace silicon solar cells, but despite the very promising future of these perovskite solar cells, the presence of water-soluble toxic lead content is a growing concern in the scientific community and a major bottleneck for their commercialization. The less toxic, tin-based perovskite solar cells are promising alternatives for lead-free perovskite solar cells. Like lead-based perovskite, the general chemical formula composition of tin-based perovskite is ASnX3, where A is a cation and X is an anion (halogen). It is evident that tin-based perovskites, being less-toxic with excellent photoelectric properties, show respectable performance. Recently, numerous studies reported on the fabrication of Sn-based perovskite solar cells. However, the stability of this novel lead-free alternative material remains a big concern. One of the many ways to stabilize these solar cells includes addition of dopants. In this context, this article summarizes the most important fabrication routes employing dopants that have shown excellent stability for tin-based perovskite photovoltaics and elaborates the prospects of lead-free, tin based stable perovskite photovoltaics.


2021 ◽  
Author(s):  
Li Xia ◽  
JianYang Ling ◽  
Zhen Xu ◽  
Rongshan Bi ◽  
Wenying Zhao ◽  
...  

Abstract On the platform of general chemical process simulation software(it was named Optimization Engineer, OPEN), a general optimization algorithm for chemical process simulation is developed using C++ code. The algorithm is based on Sequential Quadratic Programming (SQP). We adopt the activity set algorithm and the rotation axis algorithm to generate the activity set to solve the quadratic programming sub-problem. The active set method can simplify the number of constraints and speed up the calculation. At the same time, we used limited memory BFGS algorithm (L-BFGS) to simplify the solution of second derivative matrix. The special matrix storage mode of L-BFGS algorithm can save the storage space and speed up the computing efficiency. We use exact penalty function and traditional step-size rule in the algorithm. These two methods can ensure the convergence of the algorithm, a more correct search direction and suitable search step. The example shows that the advanced optimization function can meet the requirements of General Chemical Process Calculation. The number of iterations can reduce by about 6.0% . The computation time can reduce by about 6.5% . We combined this algorithm with chemical simulation technology to develop the optimization function of chemical engineering simulation. This optimization function can play an important role in the process optimization calculation aiming at energy saving and green production.


Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1300
Author(s):  
Daniil N. Olennikov ◽  
Christina S. Kirillina ◽  
Nadezhda K. Chirikova

Willowherb (Epilobium angustifolium L., family Onagraceae) is a well-known food and medicinal plant used after fermentation as a source of beverages with high antioxidant potential. Despite this long history of use, only a few papers have described the chemical profile and bioactivity of fermented willowherb tea in general. To understand the basic metabolic differences of non-fermented and fermented E. angustifolium leaves, we used general chemical analysis, high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection assay, and an isolation technique. As a result, the content of 14 chemical groups of compounds was compared in the two plant materials; 59 compounds were detected, including 36 new metabolites; and a new water-soluble phenolic polymer of melanoidin nature was isolated and characterized. The fundamental chemical shifts in fermented E. angustifolium leaves relate mainly to the decrease of ellagitannin content, while there is an increase of melanoidin percentage and saving of the antioxidant potential, despite the significant changes detected. The strong antioxidative properties of the new melanoidin were revealed in a series of in vitro bioassays, and a simulated gastrointestinal and colonic digestion model demonstrated the stability of melanoidin and its antioxidant activity. Finally, we concluded that the new melanoidin is a basic antioxidant of the fermented leaves of E. angustifolium, and it can be recommended for additional study as a promising food and medicinal antioxidant agent.


2021 ◽  
Vol 11 (14) ◽  
pp. 6615
Author(s):  
Olga Zubkova ◽  
Aleksey Alexeev ◽  
Arseniy Polyanskiy ◽  
Kirill Karapetyan ◽  
Olga Kononchuk ◽  
...  

The solution of the sludge utilization problem and yield increase at processing plants have great importance today all over the world. Disasters associated with the tailings dams failures have madeus develop technologies of tailings sludge utilization as a commercial product, reducing the environmental damage on the regions of mineral extraction. This research aimed to provide new data, methods and an analytical approach to solve the saponite sludge accumulation problem on mining enterprises with silicate coagulant to increase the rate of cycle water clarification for the enrichment process and the recycling of sludge to reduce its hazardous effect. Samples were taken in the deposit located in the north of the European part of Russia, where diamond bearing ore contain montmorillonite minerals, mostly saponite, which is considered to be a perspective secondary product. The content of this mineral in the sludge is above 20 wt.%. Saponite is a clay mineral with the general chemical formula (Ca,Na)0.3(Mg, Fe2+)3(Si, Al)4O10(OH)2·4H2O. The mineral has high adsorption, ion exchange, and catalytic and filtration properties; due to the developed diffuse layer, saponite particles are highly stable in an aqueous medium—the resulting suspension is highly stable and has slow sedimentation. During the research, a positive effect on the sedimentation process of clay saponite particles was established, due to the introduction of a coagulant containing 70% tricalcium silicate, at a dosage of 2 g/dm3 coagulant; the degree of purification of water containing the saponite clay suspension is 99%. The condensed sediment after the thermal drying and with the limestone addition can be used again as a coagulant or secondary product with enhanced properties;therefore, the sludge will be processed, and not stored.


2021 ◽  
Vol 59 (4) ◽  
pp. 763-769
Author(s):  
Hexiong Yang ◽  
Ronald B. Gibbs ◽  
Cody Schwenk ◽  
Xiande Xie ◽  
Xiangping Gu ◽  
...  

ABSTRACT A new mineral species, liudongshengite, ideally Zn4Cr2(OH)12(CO3)·3H2O, has been found in the 79 mine, Gila County, Arizona, USA. It occurs as micaceous aggregates or hexagonal platy crystals (up to 0.10 × 0.10 × 0.01 mm). The mineral is pinkish and transparent with white streak and vitreous luster. It is brittle and has a Mohs hardness of ∼1.5, with perfect cleavage on (001). No twinning or parting is observed macroscopically. The measured and calculated densities are 2.95 (3) and 3.00 g/cm3, respectively. Optically, liudongshengite is uniaxial (−), with ω = 1.720 (8), ε = 1.660 (7) (white light). An electron microprobe analysis, combined with the carbon content measured using an elemental combustion system equipped with mass spectrometry, yielded the empirical formula (Zn3.25Mg0.17Cr2.58)Σ6.00(OH)12(CO3)1.29·3H2O, based on (M2+ + M3+) = 6 apfu, where M2+ and M3+ are divalent and trivalent cations, respectively. Liudongshengite belongs to the quintinite group within the hydrotalcite supergroup and is the Cr-analogue of zaccagnaite-3R, Zn4Al2(OH)12(CO3)·3H2O. It is trigonal, with space group Rm and unit-cell parameters a = 3.1111(4), c = 22.682(3) Å, and V = 190.12(4) Å3. The crystal structure of liudongshengite is composed of positively charged brucite-like layers, [M2+1–xM3+x(OH)2]x+, alternating with negatively charged layers of (CO3)2–·3H2O. Compared to other minerals in the quintinite group, liudongshengite is remarkably enriched in M3+, with an M2+:M3+ ratio of 1.33:1. Like zaccagnaite-3R and many other hydrotalcite-type minerals, liudongshengite may also possess polytypes, as a series of synthetic hydrotalcite-type compounds with a general chemical formula [Zn4Cr2(OH)12]X2·4H2O, where X = Cl–, NO3–, or ½ SO42–, but with unit-cell parameters different from those for liudongshengite, have been reported previously.


Author(s):  
Pedro Magalhães ◽  
Rosário M. Domingues ◽  
Eliana Alves

Background: Some plant seeds and berries have gained increased recognition due to their wide variety of bioactive compounds. Many of these foods are rich in lipids with high nutritional value, of which n-3 and n-6 essential fatty acids stand out. However, knowledge of these foodstuffs’ chemical composition and biological activity and their value as a source of healthy lipids is far from being fully explored. Objective and Methods: The benefits of the intake of hemp seeds, flaxseed and açaí berries, considered functional foods, have been compiled in this review. Likewise, their general chemical composition will be described to evaluate their relevance in a healthy diet, highlighting their lipid components and nutritional lipid indices. Results and Conclusion: The fibres and essential fatty acids of hemp seeds and flaxseed and the antioxidant properties of açaí berries provide them protective roles against several chronic non-communicable diseases and represent significant beneficial effects that add value to these healthy natural products. More research is needed to deepen the knowledge on their lipids’ molecular composition and bioactivity.


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